Telephone-transmitter



( No Model.)

G. M. HOPKINS.

TELEPHONE TRANSMITTER.

No. 258,757. I Patented May 30, 1882.

WITNESSES INVENTOR:

' ATTORNEYS.

N PETERS, Phaln-Lilhngnphur. wm'mmn, D. c

, llm'rnn STATES PATENT OFFICE.

GEORGE M. HOPKINS, OF BROOKLYN, NEW YORK.

TELEPHONE=TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 258,757, dated May 30, 1882.

Application filed March 30, 1852. (Nomodeh) To all whom it may concern Be it known that I, GEORGE M. HOPKINS, of Brooklyn, in the county of Kings and State of New York, have invented an Improved Telephone-Transmitter, of which the following is a specification.

In my improved telephone-transmitter a vibratory diaphragm carries a button of hard carbon having a plane face, in contact with which'a similar button of hard carbon is held by threads of flexible material when the diaphragm is at rest. The two hard-carbon buttons or electrodes are placed in a battery-circuit in which there is a receivingtelephone, or the primary wire of an induction-coil, the secondary wire of which is connected electrically with a distant receiving-telephone.

Figure 1 in the drawings is a rear elevation, and Fig. 2 is a vertical transverse section taken on line no a; in Fig. 1.

Like letters of reference indicate like parts in the two figures of the drawings.

The diaphragm A, of thin iron or other suitable material, is clamped tightly in a cell, B, consisting of the mouth-piece O and ring D, these two parts being fastened together by screws, as in the drawings, or otherwise, as may be desired. A hard-carbon button, E, is secured to the center of the diaphragm A by a small bolt. The surface of this button E remote from the diaphragm is made as nearly plane as possible, and is highly polished. A hard-carbon button, F, of about the same size as the button E, is clamped by four ears, to, projecting from the brass disk G, and is suspended in the present case by three threads, 11, of silk, tied in eyes 0, projecting from the edge of the disk G. These silk threads I) pass through eyes cl, projecting from the inner edge of the ring D and are wound upon the screws H. The hard-carbon button F has a plane face, which is held in light contact with the plane face of the carbon-button E by a slight tension of the threads b, the outer ends of the threads being somewhat nearer the diaphragm than their inner ends to insure drawing the' carbon button F against the carbon button E with a very gentle pressure. The carbon button E communicates by a wire, 6, with the circuit, including the battery Hand primary wire of the induction coil I, the primary of the induction-coil being connected with the carbon button F by a wire,f. The secondary wire 9 of the induction-coil I is connected with the ground K and with the line-wire L, leading to a distant telephone-receiver.

Vhen words are spoken in the vicinity of the diaphragm the relative positions of the carbon buttons E and F are changed so as to affect the primary current sufficiently to produce audible effects in the distant receivingtelephone.

Although I have shown and described three suspending-threads for holding the carbon button 1*, I do not limit or confine my invention to this number, as I may in some cases employ only two such threads, while in other cases I may use four or more.

I claim- The combination, with a plane-faced hardcarbon button carried by the diaphragm, of a vibratory electrode suspended by two or more threads, serving the double purpose of suspending a-nd pressing the button E into contact with the button E, substantially as described.

GEO. M. HOPKINS. Witnesses:

O. SEDGWIOK, (J. L. ToPLiFF. 

